Construction of Cu-Modified g‑C<sub>3</sub>N<sub>4</sub> Nanosheets for Photoinduced CO<sub>2</sub> Reduction\nto CO and Selectivity Mechanism Insight

Graphite\npolymeric carbon nitride (PCN) has been extensively applied\nto photocatalytic CO<sub>2</sub> reduction reactions, which are expected\nto enhance the reaction activity and improve product selectivity by\nintroducing transition metals. In this work, we successfully prepared\nCu-modified PCN (Cu-PCN) by a thermal polymerization approach and\nconducted a systematic and comprehensive exploration of the photocatalytic\nreduction of CO<sub>2</sub> and selective generation of CO reactions.\nA series of experiments and DFT results attest that a tiny amount\nof Cu anchor on PCN, forming an active site for activating CO<sub>2</sub>, can significantly mediate the electron transport to absorbed\nCO<sub>2</sub> molecul0065s through the Cu sites and improve the efficiency\nof the light-driven CO<sub>2</sub> reduction reaction. As-designed\nphotocatalysts exhibit excellent photocatalytic reduction of CO<sub>2</sub> to a CO selectivity close to 100%. Detection of intermediates\nusing in situ FT-IR reveals that *COOH is the critical intermediate\nand is a rate-limiting step in the overall reaction, which is consistent\nwith DFT results. Our work makes up for these deficiencies in previous\nrelated research and provides a good reference for exploring the product\nselectivity of photocatalytic reduction of CO<sub>2</sub>.